The present invention relates to partial erasure of a displayed image, and more particularly to an image display apparatus capable of selectively erasing only an image having a specific attribute of a displayed image having a plurality of images having different attributes superimposed.
In a prior art partial erasure method in an image display apparatus, such as that disclosed in Japanese Patent Unexamined Publication Nos. 57-174759, 57-193855 or 59-231636, a partial area of a displayed image is designaged as an erasure area and an image in that area is erased.
However, where images having various attributes, such as text (sentences, drawings), hand-written data (data which is written or recorded as memorandum) and natural picture, are displayed on one screen in superposition, it has not been possible to selectively erase only an image having a specific attribute in a designated erasure area.
In the prior art method, the partial area of the displayed image is totally erased, and where a plurality of images having different attributes are displayed in superposition, it is not possible to erase only the image having the designated attribute. For example, where the text and hand-written text are displayed in superposition and if a partial area which contains the handwritten data is designated, not only the hand-written data but also the text are erased.